Sewage and grey water

The most important pieces of legislation covering standards around sewage are the Building Act 2004 (managed by local authorities), the Resource Management Act (RMA) 1991 (managed by regional councils), and the Health Act 1956. Public health services ensure that the Health Act is complied with and houses meet sanitary requirements. The treatment of sewage to the environment is controlled under the RMA.

The Protocol provides guidance for public health officers on the clean-up and management of sewage spills to land at non-workplace environments. 

Sewage spills to land - protocol for cleanup and management (PDF 255KB)

ESR has reported on the potential risks that the environmental presence of pharmaceuticals contaminants in wastewater may pose to human health in New Zealand. The report reviewed the literature to determine the presence of pharmaceuticals in municipal wastewater and the efficacy of the wastewater treatment processes in removing those compounds, to estimate the potential human health risks associated with exposure to pharmaceuticals during recreational use of aquatic environments impacted by wastewater discharge.

Assessment of the presence of pharmaceuticals in, and removal from, municipal wastewater in Aotearoa New Zealand - ESR

Reusing greywater collected from your bath, shower, or washing machine can provide an alternate water source, but as grey-water can still be contaminated with bacteria or chemicals, there are some considerations on how to safely use as a water source for your garden. Follow these guidelines to minimise any risks to you, your whānau and your garden.

You can manually water the garden by:

✓  using a bucket in the kitchen sink, bath or shower to collect the cool water while you’re waiting for it to run warm, to water vegetables or fruit that will be eaten raw

 ✓  if you have access to the washing machine outlet pipe, collect the rinse water (it contains less contaminants than the first washing cycle) and apply to the general garden area

×    Don’t use water from the toilet, kitchen sink washing water, dishwasher (as it is highly alkaline), any source containing urine, laundry tub, or water used for soaking items contaminated with faecal matter (poo).

Some tips:

• Only vegetables that are cooked should be irrigated with greywater
• For vegetables eaten raw (e.g. lettuce, tomatoes) only use clean water collected while running the tap to get warm water
• Store unattended buckets of recycled greywater safely away from tamariki
• Take care that the bucket isn’t too heavy and that there are no spills, which can be a slip hazard
• Use a bucket only – if you want to put in place any plumbing for a more permanent solution please talk to your local and regional council first
• Water different parts of the garden to avoid build-up of contaminants from greywater
• The rinse water from the washing machine has lower concentrations of contaminants than the wash cycle - detergents may adversely affect plant growth
• Only apply greywater when it is needed, avoid run-off to the surrounding area, and make sure it dries out before entering the area
• Wash and dry your hands or use hand sanitiser after handling greywater
• Don’t store greywater – use it within 24 hours or bacteria will grow and cause odour
• Don’t recycle greywater when someone in the household has a tummy upset
• Don’t use greywater on vegetables which are eaten raw, or in areas where fruit drop from the tree
• Don’t use greywater in areas where children play

ESR has compiled a guidance document to support public health officers to evaluate policies and consents for greywater re-use.  

Risk framework to evaluate greywater reuse policies and consents - ESR (PDF 7.5MB)